ASTM standards DD5515-97, “Standard Test Method for the Determination of Swelling Properties of Bituminous Coal” and D720-91 “Standard Test Method for Free Swelling Index of Coal” both define conditions for measuring the inherent property of coals to “swell” upon heating in an uncontrolled combustion situation. Hence, the propensity of coal to swell is well known in the prior art. To the best of our knowledge, however, no one has attempted to take advantage of this property of coals to swell by controllably “swelling” a coal product to obtain a highly useful, low density, porous carbon product.
Similarly, very sophisticated processes have been developed for the production of cellular foamed carbon products. Such processes often involve the use of blowing agents and the application of very high pressures in the fabrication process, and many use highly sophisticated starting materials. These materials, while very lightweight and demonstrating superior strength, tend to be relatively costly, either due to the nature of their starting materials and/or the complexity of their fabrication processes.
There exists a wide and varied class of requirements for low-density materials in the construction, aerospace, transportation, metal processing and other industries for which low-density materials are constantly being developed. Many of these materials exhibit properties such as fire resistance that make them uniquely suited to their end use application. In many applications, however, the aforementioned relatively high cost, low-density materials cannot be used because the final application will simply not justify their relatively high cost.
Accordingly, it would be most desirable if a relatively low cost, low-density material demonstrating many of the desirable characteristics of the aforementioned products, such as fire resistance, were available.